Steve,
The 1959 Alaskan started with regular serial numbering at NA001, then NB, NC etc...
The NR648 ? that ceme24 pictured is a standard 1959 Alaskan with the standard coin in them which was aluminum.
I have seen dozens of 1959 Alaskans, none have had any other coin than aluminum. Not to say any coin could have been put in them, but the standard coin was aluminum for them in 1959.
Forget the coins, date bows by the riser shape.
Like some of the early 1959 Kodiaks, some of the early Alaskans were not even drilled for a coin... I have one such un-drilled no-coin 1959 Alaskan.
The other Alaskan that ceme24 shows, looks like serial number 16N16 That bow has a thicker grip area, which is also typical on other 1960 Bear bows, Kodiak, Kodiak Special, Grizzly. Those fatter grip Alaskans that I have seen also have an aluminum coin. But again, any coin could have been put in any bow, by anyone at any time.
That 16N16 is a later 1960 serial number. The Alaskan serial numbers are like the Kodiaks that continued the 1959 serial numbers into the early 1960 bows.
Hopefully this helps a bit.